OK, how do you connect the pvc pipes thatgo from the strainer to the connector that go to the trap? There are no threads on the bottom that attaches tot the connector...
There are no threads on the bottom that attaches tot the connector that has the nut that screw to the end
Answers: The tailpiece (the pipe attached to the sink drain) have no threads; it is simply inserted into the top of the trap, where nearby is a nut and a plastic washer. Line things up nicely, later tighten the nut hand tighy and use a wrench to tighten it slightly more -- no more than an eighth of a turn.
draw it out in print and take that into the plumbing supply or builders supply or hardware store and show them. You are probably missing a few things...similar to a nylon compression ring and another fitting.